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Re: [patch] Fix PR tree-optimization/86514
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Eric Botcazou <ebotcazou at adacore dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 16 Jul 2018 10:36:03 +0200
- Subject: Re: [patch] Fix PR tree-optimization/86514
- References: <3018517.UiVXHDucIc@polaris>
On Mon, Jul 16, 2018 at 9:52 AM Eric Botcazou <ebotcazou@adacore.com> wrote:
>
> Hi,
>
> this is a regression present on the mainline and 8 branch in the form of wrong
> code generated for an Ada program manipulating bit-packed boolean array types.
>
> The problem is in the new range optimization code of the reassoc pass: from
>
> _64 = _63 | 4;
> _73 = _64 & 191;
> _76 = _64 >> 6;
> _77 = (boolean) _76;
> _78 = (boolean) _64;
> _79 = _77 | _78;
>
> it deduces:
>
> Optimizing range tests _76 +[0, 0] and _64 +[0, 0]
> |...]
> _64 = _63 | 4;
> _73 = _64 & 191;
> _76 = _64 >> 6;
> _90 = _76 | _64;
> _19 = _90 != 0;
> _77 = (boolean) _76;
> _78 = (boolean) _64;
> _79 = _19;
>
> which is not equivalent. The proposed fix is to avoid bypassing a conversion
> to a boolean type from a type with greater precision in init_range_entry.
>
> Tested on x86_64-suse-linux, OK for the mainline?
OK for trunk and branch.
Thanks,
Richard.
>
> 2018-07-16 Eric Botcazou <ebotcazou@adacore.com>
>
> PR tree-optimization/86514
> * tree-ssa-reassoc.c (init_range_entry) <CASE_CONVERT>: Return for a
> conversion to a boolean type from a type with greater precision.
>
>
> 2018-07-16 Eric Botcazou <ebotcazou@adacore.com>
>
> * gnat.dg/opt73.adb: New test.
>
> --
> Eric Botcazou